This invention relates to a device and method for illuminating photographic color slide images that are to be photographed by a digital camera or film camera for duplication. Although much of the description of the invention relates to the use of digital cameras for providing graphic inputs to computer processing, the invention is equally applicable to the use of film cameras for duplicating photographic slides. Accordingly, as used herein, such terms as xe2x80x9ccopy,xe2x80x9d xe2x80x9ccopied,xe2x80x9d xe2x80x9ccopying,xe2x80x9d xe2x80x9ccopier,xe2x80x9d etc., refer to either or both types of photography. The device preferably uses sunlight as the source of illumination for true daylight color balance.
With the advent of digital photography and computer manipulation of digital imagery, several types of scanning systems have evolved to convert film-based photographic images to digital formats. Most common is the flat bed color scanner in which photo prints and other flat art are illuminated by artificial light and scanned rectilinearly by light reflected therefrom. Photographic slides are likewise scanned rectilinearly using transmitted light from an artificial internal lamp.
Scanners of these two types are costly, time-consuming to use, and do not deliver precise sunlight type color balance because of the artificial lamping used. The resultant computer-printed color images must be color-adjusted to approach the desired color realism. Digital cameras can be used to record all types of flat art for computer inputs. Daylight color balance can be achieved by placing the flat art in a sunlit position for photographing. Color transparencies, 35 mm slides in particular, can be copied by placing them on a light source several times brighter than the customary slide viewers in use today. The bright backlighting enables the digital camera in macro mode to auto-expose and auto-focus on the image within the slide. To avoid image blurring, the backlit slide and the camera must be rigidly connected mechanically to prevent relative movement therebetween during shutter manipulation by hand.
One digital camera manufacturer, Nikon, provides as an accessory to one specific camera model, the Nikon xe2x80x9cCoolpixxe2x80x9d, a cylindrical hood that mounts onto the lens ring of the camera, having a circular diffuse transmitting front face behind which 35 mm slides can be passed through in a slidable rack like slide projectors of old. The camera records the image digitally from whatever strong light source is used. This accessory is connected only by friction and is awkward to use without incurring undersirable camera wear and tear. Because it must be pointed in the direction of the sun to receive sunlight, the camera monitor screen is very difficult to observe against the bright sunlit background.
There is nothing on the market in the nature of a kit or system for solar slide copying to use on cameras from different manufacturers having differing camera mounting geometries. The current invention solves this problem simply and efficiently.
This invention provides a tabletop workstation system that firmly mounts a camera to focus on a diffuse light-transmissive aperture, the size of a 35 mm slide, contained in one panel of a three-sided light diffuser chamber. This chamber receives light from the sun, or a bright halogen spot lamp, incident on the three white diffusely reflecting surfaces from either the left or right side of the workstation""s axis. The light diffuser chamber comprises two hinged upright panels inserted into grooves in the base panel. The upright panels and the base panel redirect the incident light onto the aperture for a wide range of incoming light directions. Ideal slide aperture illuminance obtains from light directions varying from 40 degrees horizontally and 50 degrees vertically, permitting the camera to auto-focus and auto-expose at shutter speeds ranging from {fraction (1/60)} to {fraction (1/250)} second.
With the addition of a rectangular shroud having a front opening slightly larger than the size of the diffuser chamber, ambient light is suppressed, enabling the operator to comfortably view the camera""s monitor to operate zoom function for the desired cropping. A pair of legs at the rear of the workstation tilts it forward so the slide to be photographed simply lies against the bright diffuser panel without need for any mounting fixture.
Bright sunlight incident upon a diffuse white surface provides an illuminance of about 6000 foot-Lamberts, too bright for the human eye to view comfortably, and much brighter than required for slide illumination. The three-sided diffuser chamber reduces the brightness provided to the slide by a factor of 3 or 4 from that of direct sunlight to achieve optimum brightness for camera operation.
This invention preferably provides a slotted rack for the workstation that is adaptable by means of shims and mounting bolts to accommodate different camera parameters: lens axis height above camera base; minimum macro focus distance; camera mounting distance from lens axis, left or right. With such flexibility, most of the digital cameras with macro zoom capability work well with this invention.